Field of the Invention
The invention relates to the field of wafer-level manufacturing methods in general, and in particular to the manufacture of devices in which one or more components are attached to a substrate. In a specific view, it relates to the field of micro-optics. In another specific view, it relates to replication methods, in particular to embossing-type processes. The invention relates to methods according to the opening clauses of the claims and to the so-produced devices.
Description of Related Art
Definition of Terms
“Active optical component”: A light sensing or a light emitting component. E.g., a photodiode, a photodiode array, an image sensor, an LED, an OLED, a laser chip. An active optical component can be present as a bare die or in a package, i.e. as a packaged component.
“Passive optical component”: An optical component redirecting light by refraction and/or diffraction and/or (internal and/or external) reflection such as a lens, a prism, another diffractive or refractive structure, a mirror, or an optical system, wherein an optical system is a collection of such optical components possibly also comprising mechanical elements such as aperture stops, image screens, holders.
“Opto-electronic module”: A component in which at least one active and at least one passive optical component is comprised.
“Replication”: A technique by means of which a given structure or a negative thereof is reproduced. E.g., etching, embossing (imprinting), casting, molding.
“Wafer”: A substantially disk- or plate-like shaped item, its extension in one direction (z-direction or vertical direction or stacking direction) is small with respect to its extension in the other two directions (x- and y-directions or lateral directions). Usually, on a (non-blank) wafer, a plurality of like structures or items are arranged or provided therein, typically on a rectangular grid. A wafer may have openings or holes, and a wafer may even be free of material in a predominant portion of its lateral area. A wafer may have any lateral shape, wherein round shapes and rectangular shapes are very common. Although in many contexts, a wafer is understood to be prevailingly made of a semiconductor material, in the present patent application, this is explicitely not a limitation. Accordingly, a wafer may prevailingly be made of, e.g., a semiconductor material, a polymer material, a composite material comprising metals and polymers or polymers and glass materials. In particular, hardenable materials such as thermally or UV-curable polymers are interesting wafer materials in conjunction with the presented invention.
“Lateral”: cf. “Wafer”
“Vertical”: cf. “Wafer”
“Light”: Most generally electromagnetic radiation; more particularly electromagnetic radiation of the infrared, visible or ultraviolet portion of the electromagnetic spectrum.
From EP 1 837 165 A1, methods for molding optical elements are known in which tools are used that have an overflow volume. Various kinds of such tools are described therein that shall control the flow of replication material.
In WO 2009/076 786, ways of attaching a spacer to a substrate are disclosed.
The invention emerged from the desire to be able to produce optical elements on a substrate under strong space restrictions. Miniaturization and the need to provide more and more functionality per substrate area are important issues in micro-optics as well as in other areas such as microelectronics, micromechanics and microfluidics. In addition, when elements or components, e.g., optical elements, shall be produced in mass production, a high process stability must be reached in order to achieve a suitable yield and thus an efficient manufacturing process.
In particular, it may occur that an element or component, e.g., an optical element such as a lens element, shall be located close to another item such as to another optical element or to a portion of a spacer for keeping two wafers or substrates in a well-defined mutual distance. More particularly, such an element or component may be manufactured using an embossing-type process, in which a replication tool is used for manufacturing the element or component on a substrate. And therein, it is possible to provide that more replication material is used in such an embossing-type process than finally present in the element or component itself. Particularly, it is possible in such an embossing-type process to produce an element or component which comprises the element or component and, in addition, a surrounding portion which is present around the element or component. One reason for providing the additional amount of replication material (excess replication material) and the surrounding portion, respectively, is that a dispensing process in which the replication material is applied between the replication tool and the substrate (typically to one or both of them) has a limited precision. And furthermore, the surrounding portion can make possible to control the flow of the replication material during the embossing process. The provision of excess replication material can contribute to prevent the formation of voids in the element or component.